Carbon

"Behold.... The city of Carbon. Jewel of the Eden System, and center of all trade in the fourth quadrant." Albert led his company out of the cave and into the daylight.

The four of them all threw up their arms or hands to shield their eyes to the fractured lights cast about. Like pieces of rainbows, they littered the smooth polished stone ground, and when they finally looked up to take it all in, all but Albert gaped in awe. Diamond buildings rose to the sky, open air to the elements of weather, draped with white linen that swayed and billowed in the breeze.

Beds of tropical shrubs were shaded with palm trees, most likely introduced from earth, and admittedly introduced seamlessly. Vines grew on marble arches and pillars, heavy with unblemished fruit. Pot lights lined the sidewalks, unlit and still somehow adding to the aesthetics of it all.

"How is this possible?" The only girl of Albert's chosen few spoke up.

Albert turned to face his group.
"How do you think?"